POACEAE 153 
Midnerve of the flowering scale pubescent the whole length, or 
nearly so. 
Flowering scales about 2.5 mm. long, obtuse. 7. P. sylvestris. 
Flowering scales about 4 mm. long, acute. 8. P. Wolfii. 
** Panicle contracted, its branches erect or nearly so: spikelets crowded. 
Flowering scales strongly pubescent at the base with very long 
crimped hairs, the midnerve and lateral nerves pubescent. 9. P. arachnifera. 
Flowering scales with fewer crimped hairs at the base, the nerves 
all glabrous. 10. P. glabrescens. 
b. Flowering scales with no crimped hairs at the base. 
Panicle loose and open, its branches long and widely spreading and spike- 
let-bearing only above the middle. 11. P. autumnalis. 
Panicle contracted, its branches short and erect or nearly so, spikelet- 
bearing to the base or nearly so. 12. P. pratericola. 
B. Plants dull bluish green, with long stout often branching rootstocks : stems 
much compressed. 13. P. compressa. 
l. Poa ánnua L. Stems 5-30 cm. tall, erect, or decumbent at the base: leaf-sheaths 
loose, usually overlapping ; blades 1-10 em. long, 1.5-3 mm. wide: panicle 1-10 cm. long, 
its branches spreading: spikelets 3-5-flowered, 3-5 mm. long, the flowering scales 2.5-3 
mm. long. 
In waste and cultivated places nearly throughout North America. Naturalized from Europe. 
Native also of Asia. Spring to fall. 
2. Poa Chapmaniàna Scribn. Stems 7-15 cm. tall, erect, rigid : leaf-sheaths tight, 
mostly at the base of the stem; blades 1-2.5 cm. long, 2 mm. wide or less: panicle 2.5-5 
em. long : spikelets 3-7-flowered, 2.5-3 mm. long, the flowering scales obtuse, webbed at the 
e su sometimes with hairs on the more prominent nerves. [P. cristata Chapm., not 
Y alt. 
In dry soil, Kentucky and Tennessee to Georgia, Florida and Alabama. Spring. 
3. Poatriviàlis L. Stems 3-9 dm. tall, usually decumbent at the base : leaf-sheaths 
very rough ; blades 5-18 em. long, 2-4 mm. wide, rough: panicle 1-1.5 dm. long: spike- 
lets 2-3-flowered, 3 mm. long, the scales acute, the flowering scales 2-3 mm. long, 5-nerved, 
the intermediate nerves prominent. 
In meadows and waste places, New Brunswick to Michigan and Georgia. Naturalized from 
Europe. Summer. 
4. Poa alsódes A. Gray. Stems 2-8 dm. tall: leaf-blades usually rough, 2-4 mm. 
wide, those on the stem 5-20 cm. long, the basal ones longer: panicle 8-20 cm. long, its 
branches spikelet-bearing at the ends : spikelets 2-3-flowered, about 5 mm. long, the flow- 
ering scales acute, about 4 mm. long, the intermediate nerves very faint. 
In woods and thickets, Nova Scotia to Ontario, Minnesota, North Carolina and Tennessee. Spring 
and summer. 
5. Poa praténsis L. Stems 3-12 dm. tall: leaf-blades smooth or rough, 1-6 mm. 
wide, those on the stem 5-15 em. long, the basal much longer : panicle 6-20 cm. long, us- 
ually pyramidal: spikelets 3-5-flowered, 4-5 mm. long, the scales acute, the flowering 
scales 3 mm. long, 5-nerved. 
In meadows, fields and woods, almost throughout North America. Widely cultivated for hay. 
Also in Europe and Asia. Summer. KENTUCKY BLUE GRASS. JUNE GRASS. 
6. Poa brevifólia Muhl. Stems 3-9 dm. tall, erect : leaf-blades smooth beneath, 
rough above, 2-4 mm. wide, abruptly acute, those on the stem 1-10 em. long, the upper- 
most sometimes almost wanting: panicle 6-13 cm. long, its branches widely spreading or 
often reflexed, spikelet-bearing at the ends: spikelets 3-6-flowered, 5-7 mm. long, the 
flowering scales 4-5 mm. long, obtuse, the intermediate nerves prominent. 
In rocky woods, southeastern New York to Illinois, North Carolina and Tennessee. Spring and 
summer. 
7. Poasylvéstris A. Gray. Stems 3-9 dm. tall, slender: leaf-blades smooth beneath, 
rough above, 2-6 mm. wide, those on the stem 4-15 em. long, the basal much longer : 
panicle 7-18 cm. long, the branches spreading or ascending, sometimes reflexed when old, 
spikelet-bearing at the ends: spikelets 2-4-flowered, 2-4 mm. long, the flowering scales 
about 2.5 mm. long, obtuse. 
In thickets and meadows, New York to Wisconsin, Nebraska, Georgia and Louisiana. Summer. 
8. Poa Wólfii Scribn. Stems tufted, 3-9 dm. tall: leaf-blades rather lax, flat, 2-3 
mm. wide, those on the stem 5-10 em. long, the basal ones longer : panicle 7-15 em. long, 
its branches long and lax, dreoping, spikelet-bearing toward the end : spikelets 2-4-flow- 
ered, 5-6 mm. long, the acute flowering scales about 4 mm. long, strongly pubescent on the 
midnerve and the lateral nerves, the intermediate nerves very prominent. 
In moist soil, Illinois, Tennessee and Kansas. Summer. 
9. Poa arachnífera Torr. Stems tufted, 3-9 dm. tall: leaf-blades erect, usually 
folded when dry, smooth beneath, rough above, 4-23 cm. long, 3-6 mm. wide, abruptly 
acute: panicle dense and contracted, sometimes interrupted below, 7-16 cm. long, its 
